Incorporation of DMSO and dextran-40 into a gelatin/alginate hydrogel for controlled assembled cell cryopreservation

A new cell cryopreservation strategy for cell-assembling constructs was proposed. With this strategy, different concentrations of dimethysulfoxide (DMSO) and dextran-40 were directly incorporated into the cell/gelatin/alginate systems, prototyped according to a predesigned structure, cryopreserved at −80 °C for 10 days and followed a thawing process at 17 °C. The rheological properties, bonding water contents and melting points of the gelatin/alginate hydrogel systems were changed with the addition of different amounts of DMSO. The microscopy analysis, (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrasodium bromide (MTT) and hematoxylin and eosin (HE) staining indicated that the cell numbers were progressively in a selected DMSO concentration range. With DMSO 5% (v/v) alone, the metabolic rate in the construct attained (81.3 ± 5.7)%. A synergistic effect was achieved with the combination of the DMSO/gelatin/alginate and dextran-40/gelatin/alginate hydrogel systems. These results indicated that the inclusion of DMSO and dextran-40 in the hydrogel could effectively enhance the cell preservation effects. This cryopreservation strategy holds the ability to be widely used in organ manufacturing techniques.     

Female mating status does not affect male mating behavior in the West Indian sweetpotato weevil, Euscepes postfasciatus

Because multiple mating by females encourages sperm competition, the assessment of female mating status before insemination is important for males in order to avoid the risk of sperm competition or to intensify sperm competition. When interacting with females before sperm transfer, males can alter their mating tactics according to the risk or intensity of sperm competition. Information on how mating systems are associated with sperm competition is essential for sterile insect technique eradication programs, which depend on successful mating of released sterile males with wild females. We tested whether males of the West Indian sweetpotato weevil, Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae), adjusted their mating behavior in response to female mating experience and/or age. As virgin/young female weevils accepted males more easily than non-virgin/old females, assessing females before insemination can be adaptive for male weevils. We found that E. postfasciatus males were unable to adjust their mating tactics in response to female mating status. Although this mating strategy would be costly for individual male weevils, the ability in males to discriminate female mating status can prevent the chance of mating with already-mated females containing the sperm of wild male(s). Therefore, the mating tactics of male E. postfasciatus are advantageous for sterile insect technique eradication programs.     

Virtual Tangential-fields Arc Therapy (ViTAT) for whole breast irradiation: Technique optimization and validation

PurposeTo test the performances of a volumetric arc technique named ViTAT (Virtual Tangential-fields Arc Therapy) mimicking tangential field irradiation for whole breast radiotherapy.MethodsViTAT plans consisted in 4 arcs whose starting/ending position were established based on gantry angle distribution of clinical plans for right and left-breast. The arcs were completely blocked excluding the first and last 20°. Different virtual bolus densities and thicknesses were preliminarily evaluated to obtain the best plan performances. For 40 patients with tumor laterality equally divided between right and left sides, ViTAT plans were optimized considering the clinical DVHs for OARs (resulting from tangential field manual planning) to constrain them: ViTAT plans were compared with the clinical tangential-fields in terms of DVH parameters for both PTV and OARs.ResultsDistal angle values were suggested in the ranges [220°,240°] for the right-breast and [115°,135°] for the left-breast cases; medial angles were [60°,40°] for the right side and [295°,315°] for the left side, limiting the risk of collision. The optimal virtual bolus had −500 HU density and 1.5 cm thickness. ViTAT plans generated dose distributions very similar to the tangential-field plans, with significantly improved PTV homogeneity. The mean doses of ipsilateral OARs were comparable between the two techniques with minor increase of the low-dose spread in the range 2–15 Gy (few % volume); contralateral OARs were slightly better spared with ViTAT.ConclusionViTAT dose distributions were similar to tangential-fields. ViTAT should allow automatic plan optimization by developing knowledge-based DVH prediction models of patients treated with tangential-fields.     

渍害胁迫下小麦生长的响应机理及调控措施研究进展

全球气候变化导致近年来渍害频发,而旱地作物小麦对渍害敏感。受气候、土壤、轮作制度等因素的影响,我国长江中下游小麦主产区的渍害灾情严重。渍害引起的土壤溶氧量降低可以导致小麦根系生长受到抑制,进而限制植株生长,最终降低小麦产量和品质。本文基于国内外相关研究,从根系呼吸代谢、水分传导、矿质养分吸收、光合作用、氧化还原代谢等方面概述了渍害胁迫抑制小麦生长的生理机理;讨论了小麦通过无氧呼吸维持能量供应和改变根系形态维持氧气供应等渍害适应机制;总结了肥料调控、生长调节剂调控和胁迫记忆等栽培措施在小麦抗渍上的应用及其机理,并对未来小麦抗渍研究进行了展望,以期为小麦的耐渍栽培和稳产高产管理提供理论支撑。     

Reliability of bulky DNA adducts measurement by the nuclease P1 32P-post-labelling technique

The aim was to assess the reliability of bulky DNA adducts measurement by means of the ³²P-post-labelling assay. The research design consisted of an intramethod reliability study. Buffy coats from 41 subjects were used to obtain two aliquots of 1–5 μg DNA for each subject; bulky DNA adducts were measured using the nuclease P1 ³²P-post-labelling technique. The reliability of the measurement was assessed by means of the intraclass correlation coefficient (ICC), the distribution of the differences between the two measurements and the limits of agreement. The estimated ICC was 0.977, with a 95% confidence interval between 0.921 and 0.977. The limits of agreement were ±0.44 (DNA adducts per 10⁸ nucleotides). Only three subjects had differences lying out of such limits. Bulky DNA adduct levels measured by the ³²P-post-labelling technique showed good reliability. Only one measurement is needed to use DNA adducts as a biomarker of exposure and, possibly, cancer risk. Besides, as a validation analysis, ³²P-post-labelling measurements can be repeated in only 20–30% of samples.     

Carcinogen DNA adducts and the risk of colon cancer: case–control study

Colorectal cancer represents 8.5% of all tumours at the King Faisal Specialist Hospital & Research Centre. Environmental and dietary carcinogens such as polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs) have long been suspected to play a prominent role in colon cancer aetiology. We designed a case–control study to test the hypothesis of whether or not the presence of DNA adducts can play a role in the aetiology of colon cancer. DNA adducts were measured in 24 cancerous and 20 non-cancerous tissue samples of newly diagnosed colon cancer patients by ³²P-post-labelling technique. Normal tissue from 19 hospital patients served as controls. The mean levels of adducts per 10¹⁰ nucleotides in cancerous and non-cancerous tissue were 151.75±217.27 and 114.81±186.10, respectively; however, only adducts in cancerous tissue were significantly higher than controls (32.78±57.51 per 10¹⁰ nucleotides) with p-values of 0.017. No BPDE-DNA adducts were found. No relationship was found between urinary cotinine as a marker of tobacco smoke and 1-hydroxypyrene as an indicator of an individual's internal dose of PAHs and DNA adducts. In a logistic regression model, only adducts in cancerous tissue were associated with the subsequent risk of colon cancer, with an odds ratio of 3.587 (95% confidence interval 0.833–15.448) after adjustment for age and the duration of living in the current region, but of a borderline significance (p=0.086). Although it is difficult to arrive at a definite conclusion from a small dataset, our preliminary results suggest the potential role of DNA adducts in the colon carcinogenesis process. Additional studies with larger sample sizes are needed to confirm our preliminary finding. It is also important to identify the structural characterization of these unknown DNA adducts in order to have a better understanding of whether or not environmental carcinogens play a role in the aetiology of colon cancer.     

Seeing and knowing in twenty-first century genetic medicine: the clinical pedigree as epistemological tool and hybrid risk technique

This paper explores the clinical pedigree as a risk technique within the context of the predictive genetic testing (PGT) clinic. We situate the PGT clinic as a site of genetic governance in that it is a site both for the production of knowledge about genetic risk and for intervening in the everyday lives of individuals and their families who learn to cultivate their relations with themselves and their biological relatives in relation to genetic risk knowledge. Drawing on literature of the pedigree as socially constructed and on notions of risk governance, we suggest that the pedigree operates as an epistemological tool and risk technique – that is, as a visual device that assists in organizing the social relations of knowledge production and aids in effecting shifts in patient subjectivity in ways that are consistent with neoliberal notions of active citizenship.     

Dithranol as a Matrix for Matrix Assisted Laser Desorption/Ionization Imaging on a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer

Mass spectrometry imaging (MSI) determines the spatial localization and distribution patterns of compounds on the surface of a tissue section, mainly using MALDI (matrix assisted laser desorption/ionization)-based analytical techniques. New matrices for small-molecule MSI, which can improve the analysis of low-molecular weight (MW) compounds, are needed. These matrices should provide increased analyte signals while decreasing MALDI background signals. In addition, the use of ultrahigh-resolution instruments, such as Fourier transform ion cyclotron resonance (FTICR) mass spectrometers, has the ability to resolve analyte signals from matrix signals, and this can partially overcome many problems associated with the background originating from the MALDI matrix. The reduction in the intensities of the metastable matrix clusters by FTICR MS can also help to overcome some of the interferences associated with matrix peaks on other instruments. High-resolution instruments such as the FTICR mass spectrometers are advantageous as they can produce distribution patterns of many compounds simultaneously while still providing confidence in chemical identifications. Dithranol (DT; 1,8-dihydroxy-9,10-dihydroanthracen-9-one) has previously been reported as a MALDI matrix for tissue imaging. In this work, a protocol for the use of DT for MALDI imaging of endogenous lipids from the surfaces of mammalian tissue sections, by positive-ion MALDI-MS, on an ultrahigh-resolution hybrid quadrupole FTICR instrument has been provided.     

植物功能基因组研究方法及进展

随着植物功能基因组研究的深入,T-DNA标签、转座子标签、反义RNA技术、基因敲除、基因陷阱和TILLING技术等多种研究方法获得了建立,并随着植物功能基因组学的不断发展而进一步完善.综述了各类研究方法的原理,并对这些方法的优缺点进行了比较与分析.     

双翅目害虫性别分离技术的研究进展及展望

在过去的几十年中,昆虫不育技术(sterile insect technique, SIT)已被用于防治农业害虫和人类健康相关的病媒害虫。相较于传统的农药控制策略,昆虫不育技术具有物种特异性和环境友好型等特点。通过释放不育雄虫的昆虫不育技术的主要障碍是在大规模饲养阶段将雄性与雌性分离,从而提高这些防治方法的成本效率,并防止释放携带和传播疾病的雌性群体。目前大多数针对双翅目害虫的遗传防治策略没有进行性别分离,少数害虫性别分离方法是基于蛹的大小或者雌雄蛹羽化时间差异进行人工识别和机械识别分离。双翅目昆虫性别决定及分化分子机制多种多样,其性别决定主要信号差异巨大,其多种性别决定基因已用于性别分离系统的开发。性比失衡性别分离策略通过破坏性别决定途径关键基因的表达获得雄性偏向后代,雌性条件性致死分离策略利用性别决定关键基因的雌雄选择性剪接差异实现性别分离,这两种性别分离策略目前正在害虫不育防治中接受大规模饲养应用评估,而基于双翅目昆虫雌雄性二态和基因标记发展的可视化性别分离策略也已成功实现多种害虫的性别分离。我们对性比失衡分离策略、雌性条件性致死分离策略和可视化性别分离策略在双翅目害虫中的研究进展进行了综述,重点评估了这些方法在雄虫大规模饲养和释放的应用潜力,以期在更完善的性别分离技术支持下为害虫防治研究取得更多突破性进展。